Go to the options menu at the beginning of the game

Open the game.
Pick New, Load or Resume Game.
When in the game, press Esc.
Click on 'options'
Hold down F1 while you key in a sequence of arrows as shown below to unlock features.

if you go into a file on the computer (cant remember which 1) you can change the weight of cars the speed of them even the default driver note: when you're changing the weight and the speed the max is 10,000. when you're driving the heaviest car aka the plow king you can send cars flying

First, open the Start menu, open Search, at the left of the window, in 'Name of/or part of folder' type 'Vivendi'. Do the same with 'Phrase in file name'. Choose 'Look in 'My Computer' (So it searches everywhere) and click 'Search'.
When it is done searching, open the folder 'The Simpsons: Hit and Run' (NOTE: do not open the FILE below it, for it will open the game and we don't want that yet). Once in the folder make a backup folder of 'Scripts' & 'Art'. Open 'Scripts' and then open 'Vehicles'. We'll start with something simple so right click 'v_famili' and choose open with Notepad (Never choose Word or something like that because Notepad is the game's scripting engine)
You should see a window pop-up titled 'Notepad v_famili (Read Only)' With Read Only on you cant alter the files. So minimize this window and highlight all the files in the 'Vehicles', right click 'Properties' and down the bottom of the new window you should see:
◘ Read only -selected-
◘ Hidden
Click the read only square and click 'Apply' then exit. Maximize v_famili and you will now see scripting codes like
setgasscale:120.00 ect. (!!!!NEVER MESS WITH setbrakescale BECAUSE IT WILL CRASH THE GAME!!!!). So play around with the codes and if you need help with the scripting/coding, PM me for more help!!!

When you are on 'hit and run' change missions. the cops wont be after you but the hit and run meter will still be flashing. DONT LET THE HIT AND RUN METER GO DOWN.Destroy as much as you like with the meter up and the cops wont come after you again until the meter goes down.

To get out of hit and run all you have to do is save your game and then load it again and you'll be back at the last mission you were at with no hit & run!!

go inside a building and hang out there until your meter has stoped flashing.

If you need to go somewhere high (the fire escape on the Entertainment District level, for example) find a car, preferably a van or truck, or even better, the fire engine (providing you own it) and hop up. If necessary, park with your door to the wall, you will come out on top of the vehicle.

On the last mission of the 1st level, you have to race Smithers through most of the level to get to Mr. Burns' mansion, starting from the nuclear power plant. You can't cut through the power plant itself because a door slams shut, blocking your way. HOWEVER, if you park your car halfway into the doorway (I used the Family Sedan), The door will slam shut on it, damaging it but not destroying it. The rear end of the vehicle hangs out and you can hop right in to take an easy short-cut to the end of the mission without a hassle.

In Level 3 the special car is found on the large ship in a large container on top of 2 other containers to get to it you climb the boxes at the back and it is a boat

In each level there is a Secret Car that can be found.
Level 1: Go to the rich neighborhood and drive to the Gold house. In front of it there is a rocket car. Homer can drive in it at high speeds but watch out, it can be destroyed very easily.
Level 2: Go to the Monorail station and walk up the stairs. When up the top, go to the first car of the Broken Monorail and get in it. You can now drive the broken Monorail along the roads.
Level 3: This is the only car that I can't give a description of. But I know it is Knightboat. Find it around the bay.
Level 4: This car is actually a four-wheeler Motorbike (Quad bike). Just go to the Trailer park as Marge and find near a caravan. It is fast but very hard to handle.
Level 5: Apu's Special Car is very easy to find. Just go to the Springfield Stadium and on a large platform, there will be a Monster Truck. You can get in it a demolish anything you may find! Mwahahaha!
Level 6: Go to Planet Hype's Roof and fall off just a bit, so you fall on the pink Cadillac that is stuck onto it's wall.
Level 7: Climb on the Tankers and Fire Trucks to reach the Roof of the 'Spooky Burger' next to the 'Spook-e-Mart' and on top there wil be a Toy RC that you can actually drive.

When playing the game, and if you are near zombies, remember that zombies count in hit and run too. That means that if you run one over, that's more yellow on the meter before you get some police cars trying to chase you down.

Ride a car as a passenger. Drive near a wasp. Get out of the car with the car between you and the wasp. The wasp will attempt to shoot you but might hit the driver knocking him/her out of the car. You can get back in the car as a passenger. You will hear the driver's voice but they won't be in the car.

pause game go to options hold f1 and press down(3), left. i think it works after you complete all missions but not sure

Boot up your game and go into system settings / options. Now go to the time settings and change the date to various special days of the year. Like 25th December or 31st October or to 31st December and you should see some suprising features changed in the game.

Right,right,left,left
this makes you blow cars up when you touch them
warning your hit and run meter goes up by about half for each car

On the c-spanker there are some green crates with some grey boxes at the back. Climb up those grey boxes, go round the front carefully and there you have it a speedboat on wheels!
(does not work on water)

Left,Left,Left,Right
this code makes you fly like a mile into the and forward

If you want to skip a mission fail the mission 5 times, after that when you fail again it will come up with skip on yhe screen!